In the field of mobile communication technologies, research and development of next generation communication systems are being conducted at a rapid pace. In a currently proposed communication system, a single carrier scheme is to be used for uplink transmission to reduce the peak-to-average power ratio while achieving a wide coverage area.
In this communication system, uplink and downlink radio resources are allocated to users depending on their channel conditions in the form of shared channels to be shared by the users. The process of allocating radio resources is called “scheduling”. In order to perform uplink scheduling properly, each user device transmits a pilot channel to a base station and the base station estimates the uplink channel conditions of the user device based on the reception quality of the pilot channel. Similarly, in order to perform downlink scheduling properly, the base station transmits a pilot channel to the user device and the user device reports information indicating the reception quality of the pilot channel (i.e., channel quality indicator (CQI)) to the base station. Then, the base station estimates the downlink channel conditions of the user device based on the CQI reported by the user device. Meanwhile, 3GPP, R1-060320, “L1/L2 Control Channel Structure for E-UTRA Uplink”, Feb. 13, 2006 discloses a frequency scheduling method where resources (time and frequency) are allocated to a control channel of a user device according to a predetermined hopping pattern.